<?php
/** Guided placement, preserving WordPress's normal review and publish workflow.
 *
 * @package AccessibleForms
 */
namespace AccessibleForms\Admin;

use AccessibleForms\Schema;
use AccessibleForms\ContentTypes;
use AccessibleForms\Extensions;
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class Placement {
	const SLUG = 'accessible-forms-placement';
	public static function invalidate( $post_id ) {
		if ( in_array( get_post_type( $post_id ), array_merge( array_keys( ContentTypes::types() ), array( 'wp_block', 'wp_template', 'wp_template_part' ) ), true ) ) {
			update_option( 'accessible_forms_placement_generation', wp_generate_uuid4(), false );
		}
	}
	/** Cache one bounded scan, then check edit permissions each time it is displayed. */
	public static function scan_batch( $form_id, $page = 1 ) {
		$key    = 'accessible_forms_placements_' . md5( get_option( 'accessible_forms_placement_generation', 'initial' ) . ':' . implode( ',', array_keys( ContentTypes::types() ) ) . ':' . absint( $form_id ) . ':' . max( 1, $page ) );
		$cached = get_transient( $key );
		if ( is_array( $cached ) ) {
			return $cached;
		}
		$query = new \WP_Query(
			array(
				'post_type'      => array_merge( array_keys( ContentTypes::types() ), array( 'wp_block', 'wp_template', 'wp_template_part' ) ),
				'post_status'    => array( 'publish', 'draft', 'private', 'pending', 'future' ),
				'posts_per_page' => 100,
				'paged'          => max( 1, $page ),
				'orderby'        => 'ID',
				'order'          => 'ASC',
			)
		);
		$ids   = array();
		foreach ( $query->posts as $post ) {
			if ( self::contains_form( $post->post_content, $form_id ) ) {
				$ids[] = $post->ID;
			}
		}
		$result = array(
			'ids'   => $ids,
			'pages' => $query->max_num_pages,
		);
		set_transient( $key, $result, HOUR_IN_SECONDS );
		return $result;
	}

	/**
	 * One line describing placement beyond this form's blocks and shortcodes,
	 * provided by an add-on. Empty when there is nothing to add.
	 *
	 * @param int $form_id Form ID.
	 * @return string
	 */
	public static function summary( $form_id ) {
		return (string) Extensions::filter( 'accessible_forms_placement_summary', '', (int) $form_id );
	}

	public static function url( $form_id, $args = array() ) {
		return add_query_arg(
			array_merge(
				array(
					'post_type' => 'accessible_form',
					'page'      => self::SLUG,
					'form_id'   => (int) $form_id,
				),
				$args
			),
			admin_url( 'edit.php' )
		);
	}

	/** Check direct blocks, shortcodes, nested groups, and synced patterns. */
	public static function contains_form( $content, $form_id, $visited = array(), $depth = 0 ) {
		if ( $depth > 32 || $form_id < 1 ) {
			return false;
		}
		if ( preg_match_all( '/' . get_shortcode_regex( array( 'accessible_form' ) ) . '/s', $content, $matches, PREG_SET_ORDER ) ) {
			foreach ( $matches as $match ) {
				if ( '[' === $match[1] && ']' === $match[6] ) {
					continue;
				}
				$attrs = shortcode_parse_atts( $match[3] );
				if ( is_array( $attrs ) && \AccessibleForms\FormKey::resolve( $attrs['id'] ?? 0, $attrs['key'] ?? '' ) === (int) $form_id ) {
					return true;
				}
			}
		}
		return self::blocks_contain( parse_blocks( $content ), (int) $form_id, $visited, $depth );
	}

	private static function blocks_contain( $blocks, $form_id, $visited, $depth ) {
		if ( $depth > 32 ) {
			return false;
		}
		foreach ( $blocks as $block ) {
			if ( 'accessible-forms/form' === $block['blockName'] && \AccessibleForms\FormKey::resolve( $block['attrs']['formId'] ?? 0, $block['attrs']['formKey'] ?? '' ) === $form_id ) {
				return true;
			}
			if ( 'core/block' === $block['blockName'] ) {
				$id = absint( $block['attrs']['ref'] ?? 0 );
				if ( $id && ! in_array( $id, $visited, true ) ) {
					$reference = get_post( $id );
					if ( $reference && 'wp_block' === $reference->post_type && 'publish' === $reference->post_status && self::contains_form( $reference->post_content, $form_id, array_merge( $visited, array( $id ) ), $depth + 1 ) ) {
						return true;
					}
				}
			}
			if ( ! empty( $block['innerBlocks'] ) && self::blocks_contain( $block['innerBlocks'], $form_id, $visited, $depth + 1 ) ) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Heading context for every known placement of a form, for content advice.
	 * Scans at most 500 posts; cached until any page, pattern or template changes.
	 *
	 * @param int $form_id Form ID.
	 * @return array{places: array, more: bool}
	 */
	public static function heading_contexts( $form_id ) {
		$key    = 'accessible_forms_headings_' . md5( get_option( 'accessible_forms_placement_generation', 'initial' ) . ':' . implode( ',', array_keys( ContentTypes::types() ) ) . ':' . absint( $form_id ) );
		$cached = get_transient( $key );
		if ( is_array( $cached ) ) {
			return $cached;
		}
		$places = array();
		$more   = false;
		for ( $page = 1; $page <= 5; $page++ ) {
			$batch = self::scan_batch( $form_id, $page );
			foreach ( $batch['ids'] as $id ) {
				$post  = get_post( $id );
				$level = $post ? self::heading_before( $post->post_content, $form_id ) : false;
				if ( false !== $level ) {
					$places[] = array(
						'id'    => (int) $id,
						'title' => $post->post_title ?: __( '(no title)', 'accessible-forms-by-accessible-org' ),
						'type'  => $post->post_type,
						'level' => $level,
					);
				}
			}
			if ( $page >= (int) $batch['pages'] ) {
				break;
			}
			$more = 5 === $page;
		}
		$result = array(
			'places' => $places,
			'more'   => $more,
		);
		set_transient( $key, $result, HOUR_IN_SECONDS );
		return $result;
	}

	/**
	 * Level of the last heading before the first placement of a form.
	 *
	 * Walks blocks in reading order, including nested blocks and synced
	 * patterns; for classic content it reads the HTML before the shortcode.
	 * A page's own title is not in its content, so a form with no earlier
	 * heading follows an assumed level-1 title.
	 *
	 * @param string $content Post content.
	 * @param int    $form_id Form ID.
	 * @return int|false Heading level (1-6), or false when the form is not in this content.
	 */
	public static function heading_before( $content, $form_id ) {
		$state = array(
			'level' => 1,
			'found' => false,
		);
		self::walk_headings( parse_blocks( $content ), (int) $form_id, $state, array(), 0 );
		return $state['found'] ? $state['level'] : false;
	}

	/**
	 * Depth-first walk that stops at the form.
	 *
	 * @param array $blocks  Parsed blocks.
	 * @param int   $form_id Form ID.
	 * @param array $state   Last level seen and whether the form was reached.
	 * @param int[] $visited Synced pattern IDs already entered.
	 * @param int   $depth   Recursion depth.
	 */
	private static function walk_headings( array $blocks, $form_id, array &$state, array $visited, $depth ) {
		if ( $depth > 32 ) {
			return;
		}
		foreach ( $blocks as $block ) {
			if ( $state['found'] ) {
				return;
			}
			$name = $block['blockName'] ?? null;
			if ( 'accessible-forms/form' === $name && \AccessibleForms\FormKey::resolve( $block['attrs']['formId'] ?? 0, $block['attrs']['formKey'] ?? '' ) === $form_id ) {
				$state['found'] = true;
				return;
			}
			if ( 'core/heading' === $name ) {
				$state['level'] = max( 1, min( 6, (int) ( $block['attrs']['level'] ?? 2 ) ) );
				continue;
			}
			if ( in_array( $name, array( 'core/post-title', 'core/query-title' ), true ) ) {
				$state['level'] = max( 1, min( 6, (int) ( $block['attrs']['level'] ?? ( 'core/post-title' === $name ? 2 : 1 ) ) ) );
				continue;
			}
			if ( 'core/block' === $name ) {
				$id        = absint( $block['attrs']['ref'] ?? 0 );
				$reference = $id && ! in_array( $id, $visited, true ) ? get_post( $id ) : null;
				if ( $reference && 'wp_block' === $reference->post_type && 'publish' === $reference->post_status ) {
					self::walk_headings( parse_blocks( $reference->post_content ), $form_id, $state, array_merge( $visited, array( $id ) ), $depth + 1 );
				}
				continue;
			}
			$html = (string) ( $block['innerHTML'] ?? '' );
			// Classic content or a freeform block containing the shortcode.
			$cut = self::shortcode_offset( $html, $form_id );
			if ( false !== $cut ) {
				self::last_html_heading( substr( $html, 0, $cut ), $state );
				$state['found'] = true;
				return;
			}
			if ( empty( $block['innerBlocks'] ) ) {
				self::last_html_heading( $html, $state );
			} else {
				self::walk_headings( $block['innerBlocks'], $form_id, $state, $visited, $depth + 1 );
			}
		}
	}

	/**
	 * Byte offset of this form's shortcode in some HTML, or false.
	 *
	 * @param string $html    HTML.
	 * @param int    $form_id Form ID.
	 * @return int|false
	 */
	private static function shortcode_offset( $html, $form_id ) {
		if ( false === strpos( $html, '[accessible_form' ) ) {
			return false;
		}
		if ( preg_match_all( '/' . get_shortcode_regex( array( 'accessible_form' ) ) . '/s', $html, $matches, PREG_SET_ORDER | PREG_OFFSET_CAPTURE ) ) {
			foreach ( $matches as $match ) {
				$attrs = shortcode_parse_atts( $match[3][0] );
				if ( '[' !== $match[1][0] && is_array( $attrs ) && \AccessibleForms\FormKey::resolve( $attrs['id'] ?? 0, $attrs['key'] ?? '' ) === $form_id ) {
					return $match[0][1];
				}
			}
		}
		return false;
	}

	/**
	 * Record the last <h1>–<h6> in some HTML.
	 *
	 * @param string $html  HTML.
	 * @param array  $state Walk state.
	 */
	private static function last_html_heading( $html, array &$state ) {
		if ( preg_match_all( '/<h([1-6])[\s>]/i', $html, $matches ) ) {
			$state['level'] = (int) end( $matches[1] );
		}
	}

	public static function shortcode( $form_id ) {
		return '[accessible_form id="' . (int) $form_id . '" key="' . \AccessibleForms\FormKey::get( $form_id ) . '"]';
	}

	public static function block_content( $form_id ) {
		return serialize_block(
			array(
				'blockName'    => 'accessible-forms/form',
				'attrs'        => array(
					'formId'  => (int) $form_id,
					'formKey' => \AccessibleForms\FormKey::get( $form_id ),
				),
				'innerBlocks'  => array(),
				'innerHTML'    => '',
				'innerContent' => array(),
			)
		);
	}

	/** Read-only link: the existing page is changed only inside the editor. */
	public static function editor_url( $page_id, $form_id, $created = false, $position = 'after' ) {
		$page = get_post( $page_id );
		if ( ! $page || ! isset( ContentTypes::types( true )[ $page->post_type ] ) || 'trash' === $page->post_status || ! current_user_can( 'edit_post', $page_id ) || ! Schema::get( $form_id ) ) {
			return '';
		}
		return add_query_arg(
			array(
				'af_insert_form'      => (int) $form_id,
				'af_page_created'     => $created ? 1 : 0,
				'af_position'         => 'before' === $position ? 'before' : 'after',
				'_af_placement_nonce' => wp_create_nonce( 'accessible_forms_place_' . $form_id . '_' . $page_id ),
			),
			get_edit_post_link( $page_id, 'raw' )
		);
	}

	/** Testable operation; handler additionally checks the submission nonce. */
	public static function create_draft( $form_id, $title, $post_type = 'page' ) {
		$type = ContentTypes::types( true )[ $post_type ] ?? null;
		if ( ! $type || ! current_user_can( $type->cap->create_posts ) ) {
			return new \WP_Error( 'accessible_forms_permission', __( 'You do not have permission to create this content type.', 'accessible-forms-by-accessible-org' ) );
		}
		if ( ! Schema::get( $form_id ) ) {
			return new \WP_Error( 'accessible_forms_unpublished', __( 'Publish the form before placing it in your content.', 'accessible-forms-by-accessible-org' ) );
		}
		$title = sanitize_text_field( $title );
		if ( '' === $title || preg_match_all( '/./us', $title ) > 200 ) {
			return new \WP_Error( 'accessible_forms_title', __( 'Enter a title of 200 characters or fewer.', 'accessible-forms-by-accessible-org' ) );
		}
		$content = use_block_editor_for_post_type( $post_type ) ? self::block_content( $form_id ) : self::shortcode( $form_id );
		return wp_insert_post(
			wp_slash(
				array(
					'post_type'    => $post_type,
					'post_status'  => 'draft',
					'post_title'   => $title,
					'post_content' => $content,
					'post_author'  => get_current_user_id(),
				)
			),
			true
		);
	}

	public static function handle_create() {
		$form_id = isset( $_POST['form_id'] ) ? absint( $_POST['form_id'] ) : 0;
		check_admin_referer( 'accessible_forms_create_page_' . $form_id );
		$title = isset( $_POST['page_title'] ) ? sanitize_text_field( wp_unslash( $_POST['page_title'] ) ) : '';
		$type  = sanitize_key( wp_unslash( $_POST['content_type'] ?? 'page' ) );
		$id    = self::create_draft( $form_id, $title, $type );
		if ( is_wp_error( $id ) ) {
			wp_die( esc_html( $id->get_error_message() ), '', array( 'back_link' => true ) );
		}
		wp_safe_redirect( self::editor_url( $id, $form_id, true ) );
		exit;
	}

	/** Only signed, authorized editor requests receive an insertion control. */
	public static function editor_assets( $hook ) {
		if ( 'post.php' !== $hook ) {
			return;
		}
		// phpcs:disable WordPress.Security.NonceVerification.Recommended -- Nonce and page capability checked below.
		$form_id  = isset( $_GET['af_insert_form'] ) ? absint( $_GET['af_insert_form'] ) : 0;
		$page_id  = isset( $_GET['post'] ) ? absint( $_GET['post'] ) : 0;
		$nonce    = isset( $_GET['_af_placement_nonce'] ) ? sanitize_text_field( wp_unslash( $_GET['_af_placement_nonce'] ) ) : '';
		$created  = ! empty( $_GET['af_page_created'] );
		$position = isset( $_GET['af_position'] ) && 'before' === sanitize_key( wp_unslash( $_GET['af_position'] ) ) ? 'before' : 'after';
		// phpcs:enable WordPress.Security.NonceVerification.Recommended
		if ( ! $form_id || ! wp_verify_nonce( $nonce, 'accessible_forms_place_' . $form_id . '_' . $page_id ) || ! current_user_can( 'edit_post', $page_id ) || ! isset( ContentTypes::types( true )[ get_post_type( $page_id ) ] ) || ! Schema::get( $form_id ) ) {
			return;
		}
		$page     = get_post( $page_id );
		$is_block = use_block_editor_for_post( $page );
		$deps     = $is_block
			? array( 'wp-dom-ready', 'wp-data', 'wp-blocks', 'wp-notices', 'wp-shortcode', 'wp-i18n' )
			: array( 'wp-dom-ready', 'wp-shortcode', 'wp-i18n' );
		wp_enqueue_script( 'accessible-forms-insert', ACCESSIBLE_FORMS_URL . 'assets/insert-form.js', $deps, \AccessibleForms\VERSION, true );
		wp_set_script_translations( 'accessible-forms-insert', 'accessible-forms-by-accessible-org' );
		wp_localize_script(
			'accessible-forms-insert',
			'AccessibleFormsPlacement',
			array(
				'formId'         => $form_id,
				'formKey'        => \AccessibleForms\FormKey::get( $form_id ),
				'pageId'         => $page_id,
				'title'          => get_the_title( $form_id ),
				'isBlock'        => $is_block,
				'created'        => $created,
				'position'       => $position,
				'alreadyPresent' => self::contains_form( $page->post_content, $form_id ),
			)
		);
		if ( ! $is_block ) {
			add_action(
				'admin_notices',
				static function () use ( $created, $position ) {
					echo '<div class="notice notice-info" id="af-placement-notice"><p role="status">' .
						esc_html(
							$created
								? __( 'Draft created with your form. Review it, then publish when ready.', 'accessible-forms-by-accessible-org' )
								: __(
									'Insert your selected form at the chosen position, then review and save your changes.',
									'accessible-forms-by-accessible-org'
								)
						) .
						'</p><p><button type="button" class="button" id="af-insert-shortcode">' .
						esc_html__( 'Insert form', 'accessible-forms-by-accessible-org' ) .
						'</button></p></div>';
				}
			);
		}
	}

	public static function render() {
		PlacementScreen::render();
	}
}